[PATCH 5.4 08/20] perf auxtrace: Fix potential NULL pointer dereference

[Greg Kroah-Hartman]

From: Leo Yan <leo.yan@xxxxxxxxxx>

[ Upstream commit b14585d9f18dc617e975815570fe836be656b1da ]

In the function auxtrace_parse_snapshot_options(), the callback pointer
"itr->parse_snapshot_options" can be NULL if it has not been set during
the AUX record initialization.  This can cause tool crashing if the
callback pointer "itr->parse_snapshot_options" is dereferenced without
performing NULL check.

Add a NULL check for the pointer "itr->parse_snapshot_options" before
invoke the callback.

Fixes: d20031bb63dd6dde ("perf tools: Add AUX area tracing Snapshot Mode")
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20210420151554.2031768-1-leo.yan@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/perf/util/auxtrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 61b8dc45428f..ae5b97427192 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -586,7 +586,7 @@ int auxtrace_parse_snapshot_options(struct auxtrace_record *itr,
 		break;
 	}
 
-	if (itr)
+	if (itr && itr->parse_snapshot_options)
 		return itr->parse_snapshot_options(itr, opts, str);
 
 	pr_err("No AUX area tracing to snapshot\n");
-- 
2.30.2